1. Related Art
Rapid Prototyping and Manufacturing (RP&M) is the name given to a field of technologies that can be used to form three-dimensional objects rapidly and automatically from three-dimensional computer data representing the objects. RP&M can be considered to include three classes of technologies: (1) Stereolithography, (2) Selective Deposition Modeling, and (3) Laminated Object Manufacturing.
The stereolithography class of technologies create three-dimensional objects based on the successive formation of layers of a fluid-like material adjacent to previously formed layers of material and the selective solidification of those layers according to cross-sectional data representing successive slices of the three-dimensional object in order to form and adhere laminae (i.e. solidified layers). One specific stereolithography technology is known simply as stereolithography and uses a liquid material that is selectively solidified by exposing it to prescribed stimulation. The liquid material is typically a photopolymer and the prescribed stimulation is typically visible or ultraviolet electromagnetic radiation. The radiation is typically produced by a laser through other sources of radiation are possible such as arc lamps, resistive lamps, and the like. Exposure may occur by scanning a beam or by controlling a flood exposure by use of a light valve that selectively transmits or reflects the radiation. Liquid-based stereolithography is disclosed in various patents, applications, and publications of which a number are briefly described in the Related Applications section hereafter.
Another stereolithography technology is known as Selective Laser Sintering (SLS). SLS is based on the selective solidification of layers of a powdered material by exposing the layers to infrared electromagnetic radiation to sinter or fuse the powder particles. SLS is described in U.S. Pat. No. 4,863,538, issued Sep. 5, 1989, to Deckard. A third technology is known as Three Dimensional Printing (3DP). 3DP is based on the selective solidification of layers of a powdered material which are solidified by the selective deposition of a binder thereon. 3DP is described in U.S. Pat. No. 5,204,055, issued Apr. 20, 1993, to Sachs.
The present invention is primarily directed to stereolithography using liquid-based building materials (i.e. medium). It is believed, however, that the techniques of the present invention may have application in the other stereolithography technologies for the purposes of maintaining more uniform building environments.
Selective Deposition Modeling, SDM, involves the build-up of three-dimensional objects by selectively depositing solidifiable material on a lamina-by-lamina basis according to cross-sectional data representing slices of the three-dimensional object. One such technique is called Fused Deposition Modeling, FDM, and involves the extrusion of streams of heated, flowable material which solidify as they are dispensed onto the previously formed laminae of the object. FDM is described in U.S. Pat. No. 5,121,329, issued Jun. 9, 1992, to Crump. Another technique is called Ballistic Particle Manufacturing, BPM, which uses a 5-axis, ink-jet dispenser to direct particles of a material onto previously solidified layers of the object. BPM is described in PCT publication numbers WO 96-12607, published May 2, 1996, by Brown; WO 96-12608, published May 2, 1996, by Brown; WO 96-12609, published May 2, 1996, by Menhennett; and WO 96-12610, published May 2, 1996, by Menhennett. A third technique is called Multijet Modeling, MJM, and involves the selective deposition of droplets of material from multiple ink jet orifices to speed the building process. MJM is described in U.S. Pat. No. 5,943,235 issued to Earl et al. on Aug. 24, 1996 and U.S. patent application Ser. No. 08/722,335, filed Sep. 27, 1996, by Leyden et al. now abandoned (both assigned to 3D Systems, Inc. as is the instant application).
Though, as noted above, the techniques of the instant invention are directed primarily to liquid-based stereolithography object formation, it is believed that the techniques may have application in the SDM technologies to maintain more uniform building environments.
Laminated Object Manufacturing, LOM, techniques involve the formation of three-dimensional objects by the stacking, adhering, and selective cutting of sheets of material, in a selected order, according to the cross-sectional data representing the three-dimensional object to be formed. LOM is described in U.S. Pat. Nos. 4,752,352, issued Jun. 21, 1988, to Feygin, 5,015,312, issued May 14, 1991, to Kinzie, and 5,192,559, issued Mar. 9, 1993, to Hull et al.; and in PCT Publication No. WO 95-18009, published Jul. 6, 1995, by Morita.
Various techniques for maintaining build temperature have been proposed. In particular various techniques have been described in European patent publication 376 571 B, published Feb. 8, 1995, by Takano et al. This publication describes the use of induction heating to heat the resin held in a vessel to a desired temperature, where the control of the heater is based on a detected temperature of the resin.
Even in view of the teachings of the above noted reference, a need remains in the art for improved techniques for controlling the temperature of the build environment.
2. Other Related Patents and Applications
The patents, applications, and publications mentioned above and hereafter are all incorporated by reference herein as if set forth in full. Table 1 provides a listing of patents and applications co-owned by the assignee of the instant application. A brief description of subject matter found in each patent and application is included in the table to aid the reader in finding specific types of teachings. It is not intended that the incorporation of subject matter be limited to those topics specifically indicated, but instead the incorporation is to include all subject matter found in these applications and patents. The teachings in these incorporated references can be combined with the teachings of the instant application in many ways. For example, the references directed to various data manipulation techniques may be combined with the teachings herein to derive even more useful, modified object data that can be used to more accurately and/or efficiently form objects. As another example, the various apparatus configurations disclosed in these references may be used in conjunction with the novel features of the instant invention.
TABLE 1 ______________________________________ Related Patents and Applications U.S. Pat. No. Issue Date Application No. Filing Date Inventor Subject ______________________________________ 4,575,330 Hull Discloses fundamental elements of stereo- Mar 11, 1986 lithography. 06/638,905 Aug 8, 1984 4,999,143 Hull, Discloses various removable support Mar 12, 1991 et al. structures applicable to stereolithography. 07/182,801 Apr 18, 1988 5,058,988 Spence Discloses the application of beam profil- Oct 22, 1991 ing techniques useful in stereolithography 07/268,816 for determining cure depth and scanning Nov 8, 1988 velocity, etc. 5,059,021 Spence, Discloses the utilization of drift correction Oct 22, 1991 et al. techniques for eliminating errors in beam 07/268,907 positioning resulting from instabilities in Nov 8, 1988 the beam scanning system 5,076,974 Modrek, Discloses techniques for post processing ob- Dec 31, 1991 et al. jects formed by stereolithography. In partic- 07/268,429 ular exposure techniques are described that Nov 8, 1988 complete the solidification of the building material. Other post processing steps are also disclosed such as steps of filling in or sand- ing off surface discontinuities. 5,104,592 Hull Discloses various techniques for reducing Apr 14, 1992 distortion, and particularly curl type distor- 07/339,246 tion, in objects being formed by stereolitho- Apr 17, 1989 graphy. 5,123,734 Spence, Discloses techniques for calibrating a scan- Jun 23, 1992 et al. ning system. In particular techniques for 07/268,837 mapping from rotational mirror coordinates Nov 8, 1988 to planar target surface coordinates are disclosed 5,133,987 Spence, Discloses the use of a stationary mirror lo- Jul 28, 1992 et al. cated on an optical path between the scan- 07/427,885 ning mirrors and the target surface to fold Oct 27, 1989 the optical path in a stereolithography system. 5,141,680 Almquist, Discloses various techniques for selectively Aug 25 1992 et al. dispensing a material to build up three- 07/592,599 dimensional objects. Oct 4, 1990 5,143,663 Leyden, Discloses a combined stereolithography sys- Sep 1, 1992 et al. tem for building and cleaning objects. 07/365,444 Jun 12, 1989 5,174,931 Almquist, Discloses various doctor blade configurations Dec 29, 1992 et al. for use in forming coatings of medium 07/515,479 adjacent to previously solidified Apr 27, 1990 laminae. 5,182,056 Spence, Discloses the use of multiple wavelengths in Jan 26, 1993 et al. the exposure of a stereolithographic medium. 07/429,911 Oct 27, 1989 5,182,715 Vorgitch, Discloses various elements of a large stereo- Jan 26, 1993 et al. lithographic system. 07/824,819 Jan 22, 1992 5,184,307 Hull, Discloses a program called Slice and various Feb 2, 1993 et al. techniques for converting three-dimensional 07/331,644 object data into data descriptive of cross- Mar 31, 1989 sections. Disclosed techniques include line width compensation techniques (erosion routines), and object sizing techniques. The application giving rise to this patent included a number of appendices that provide further details regarding stereolithography methods and systems. 5,192,469 Hull, Discloses various techniques for forming Mar 9, 1993 et al. three-dimensional object from sheet material 07/606,802 by selectively cutting out and adhering Oct 30, 1990 laminae. 5,209,878 Smalley, Discloses various techniques for reducing May 11, 1993 et al. surface discontinuities between successive 07/605,979 cross-sections resulting from a layer-by-layer Oct 30, 1990 building technique. Disclosed techniques include use of fill layers and meniscus smoothing. 5,234,636 Hull, Discloses techniques for reducing surface Aug 10, 1993 et al. discontinuities by coating a formed object 07/929,463 with a material, heating the material to cause Aug 13, 1992 it to become flowable, and allowing surface tension to smooth the coating over the object surface. 5,238,639 Vinson, Discloses a technique for minimizing curl Aug 24, 1993 et al. distortion by balancing upward curl to 07/939,549 downward curl. Mar 31, 1992 5,256,340 Allison, Discloses various build/exposure styles for Oct 26, 1993 et al. forming objects including various techniques 07/906,207 for reducing object distortion. Disclosed Jun 25, 1992 techniques include: (1) building hollow, par- and tially hollow, and solid objects, (2) achieving 08/766,956 more uniform cure depth, (3) exposing layers Dec 16, 1996 as a series of separated tiles or bullets, (4) using alternate sequencing exposure patterns from layer to layer, (5) using staggered or offset vectors from layer to layer, and (6) using one or more overlapping exposure patterns per layer. 5,321,622 Snead, Discloses a computer program known as Jun 14, 1994 et al. CSlice which is used to convert three-dimen- 07/606,191 sional object data into cross-sectional data. Oct 30, 1990 Disclosed techniques include the use of vari- ous Boolean operations in stereolithography. 5,597,520 Smalley, Discloses various exposure techniques for Jan 28, 1997 et al. enhancing object formation accuracy. Dis- 08/233,027 closed techniques address formation of high Apr 25, 1994 resolution objects from building materials and that have a Minimum Solidification Depth 08/428,951 greater than one layer thickness and/or a Apr 25, 1995 Minimum Recoating Depth greater than the desired object resolution. 08/722,335 Thayer, Discloses build and support styles for use in Sep 27, 1996 et al. a Multi-Jet Modeling selective deposition modeling system. 5,943,235 Earl, Discloses data manipulation and system con- Aug 24, 1999 et al. trol techniques for use in a Multi-Jet Model- 08/722,326 ing selective deposition modeling system. Sep 27, 1996 5,902,537 Almquist, Discloses various recoating techniques for May 11, 1999 et al. use in stereolithography. Disclosed tech- 09/790,005 niques include 1) an ink jet dispensing de- Jan 28, 1997 vice, 2) a fling recoater, 3) a vacuum appli- cator, 4) a stream recoater, 5) a counter rotat- ing roller recoater, and 6) a technique for deriving sweep extents. 5,840,239 Partanen, Discloses the application of solid-state lasers Nov 24, 1998 et al. to stereolithography. Discloses the use of a 08/792,347 pulsed radiation source for solidifying layers Jan 31, 1997 of building material and in particular the ability to limit pulse firing locations to only selected target locations on a surface of the medium. 6,001,297 Partanen, Discloses the stereolithographic formation of Dec 14, 1999 et al. objects using a pulsed radiation source where 08/847,855 pulsing occurs at selected positions on the Apr 28, 1997 surface of a building material. 08/855,125 Nguyen, Discloses techniques for interpolating origi- May 13, 1997 et al. nally supplied cross-sectional data descrip- tive of a three-dimensional object to produce modified data descriptive of the three- dimensional object including data descriptive of intermediate regions between the original- ly supplied cross-sections of data. 5,945,058 Manners, Discloses techniques for identifying features Aug 31, 1999 et al. of partially formed objects. Identifiable fea- 08/854,950 tures include trapped volumes, effective May 13, 1997 trapped volumes, and solid features of a specified size. The identified regions can be used in automatically specifying recoating parameters and or exposure parameters. 5,902,538 Kruger, Discloses simplified techniques for making May 11, 1999 et al. high-resolution objects utilizing low-resolu- 08/920,428 tion materials that are limited by their inabil- Aug 29, 1997 ity to reliably form coatings of a desired thickness due to a Minimum Recoating Depth (MRD) limitation. Data manipulation techniques define layers as primary or sec- ondary. Recoating techniques are described which can be used when the thickness be- tween consecutive layers is less than a lead- ing edge bulge phenomena. 09/061,796 Wu, et al. Discloses use of frequency converted solid Apr 16, 1998 state lasers in stereolithography. 09/154,967 Nguyen, Discloses techniques for stereolithographic Sep 17, 1998 et al. recoating using a sweeping recoating device that pause and/or slows down over laminae that are being coated over. 09/484,984 Earl, Entitled "Method and Apparatus for Forming filed et al. Three-Dimensional Objects Using Line Jan 18, 2000 Width Compensation with Small Feature Retention." Discloses techniques for forming objects while compensating for solidification width induced in a building material by a beam of prescribed stimulation. 09/246,504 Guertin, Entitled "Method and Apparatus for Stereo- Feb 8, 1999 et al. lithographically Forming Three Dimensional Objects With Reduced Distortion." Discloses techniques for forming objects wherein a de- lay is made to occur between successive exposures of a selected region of a layer. 09/248,352 Manners, Entitled "Stereolithographic Method and Ap- Feb 8, 1999 et al. paratus for Production of Three Dimensional Object Using Multiple Beams of Different Diameters." Discloses stereolithographic techniques for forming objects using multiple sized beams including data manipulation techniques for determining which portions of lamina may be formed with a larger beam and which should be formed using a smaller beam. 09/248,351 Nguyen, Entitled "Stereolithographic Method and Ap- Feb 8, 1999 et al. paratus for Production of Three Dimensional Objects Using Recoating Parameters for Groups of Layers." Discloses improved tech- niques for managing recoating parameters when forming objects using layer thicknesses smaller than a minimum recoating depth (MRD) and treating some non-consecutive layers as primary layers and treating inter- mediate layers there between as secondary layers. 09/426,416 Bishop, Entitled "Rapid Prototyping Apparatus with Feb 8, 1999 et al. Enhanced Thermal and Vibrational Stability for Production of Three Dimensional Objects." Discloses an improved Stereo- lithographic apparatus structure for isolating vibration and/or extraneous heat producing components from other thermal and vibration sensitive components. 09/247,120 Everett, Entitled "Stereolithographic Method and Ap- Feb 8, 1999 et al. paratus for production of Three Dimensional Objects Including Enhanced Control of Pre- scribed Stimulation Production." Discloses techniques forming objects using varying production of prescribed stimulation (e.g. UV radiation) and enhanced scanning con- trol. Production is reduced or eliminated dur- ing non-exposure periods (e.g. recoating, z-wait, and pre-dip delay). Production is set to a desired level based on the type of expo- sure that is desired. Scanning speed is set based on a number of criteria. Transition be- tween successive exposure vectors may be made with multiple intervening non-exposure vectors. The laser power is set using an AOM in combination with a temporary detection of beam power. 09/427,119 Kulkarni, Entitled "Stereolithographic Method and Ap- Feb 8 ,1999 et al. paratus for Production of Three Dimensional Objects Including Simplified Build Prepara- tion." Discloses techniques for forming objects using a simplified data preparation process. Selection of the various parameter styles needed to form an object is reduced to answering several questions from lists of possible choices. ______________________________________
The following two books are also incorporated by reference herein as if set forth in full: (1) Rapid Prototyping and Manufacturing: Fundamentals of Stereolithography, by Paul F. Jacobs; published by the Society of Manufacturing Engineers, Dearborn Mich.; 1992; and (2) Stereolithography and other RP&M Technologies: from Rapid Prototyping to Rapid Tooling; by Paul F. Jacobs; published by the Society of Manufacturing Engineers, Dearborn Mich.; 1996.